1. Find two financial planners that charge low comissions and are trustworthy (Look for CFP as others have recommended and CFA). Interview them and how they perform, look at their long-run performance (Min 5 years), furthermore, see if they conform to any performance presentation standards, so that they don't have a surivor bias in their performance (they only show the accounts that are still good or performed the best, not those that performed poorly or left the firm).
2. Invest 250k with each one after they have worked to get an investment performance statement that fits your friend's investment needs. One big thing they will look at is his/her *ability* to take risk as opposed to the *willingness* to take risk. 500k is a decent chunk of money to be able to take risk.
3. Check up on the advisor regularily, make sure they are not taking more or less risk than what was put down in the IPS. Also make sure they are not flipping the stocks or doing anything else to pump up comissions.
4. If your friend is within 5 years of retirement he/she should invest heavily in bonds. If he/she is within 10 years, a 60/40 mix of bonds/stocks should be appropriate. If he/she is outside of 15 years to retirement he/she should be 40/60 bonds/stocks, and 20 years+ should be somewhere around 20/80 bonds/stocks.
Now, when I say stocks I don't mean "Wow, GOOG looks good". I mean, a broad-based index fund such as a SPDR (S&P 500 index fund) or a good mix of equity funds. I am a contrarian investor and I look for value funds (those with fundamentals that are strong but the market has underpriced them). Other people look for growth (somewhat overpriced, but the idea that that price will be justified in the future by growth). Yet others are heavily into international funds. Here is a mix I would recommend for somebody still a bit risk-averse.
20% - Value equity funds
10% - Growth equity funds
10% - International equity funds
60% - investment grade bond funds
You get some exposure to risk, but at the same time you will enhance your returns. You have a strong base of bonds.
The biggest problem with people investing is that they invest the wrong way. They go for a few flashy stocks, get burned, and think the whole market sucks. Those stocks sucked because they invested on familiarity and old-news. People who don't know how to invest well need to invest for long-term growth through equity mutual funds or index funds, *NOT* specific assets. If the person doesn't invest in equity because they are now gun-shy, they will lose out on a lot of money.
If you want to discuss further, feel free to PM me. I personally do not do portfolio management, but I have passed all 3 levels of the CFA program on the 1st try and I work in capital management for a fortune 100 company. I am not some guy who just read a couple books.